bundle2: implement consume() API on unbundlepart
We want bundle parts to not be seekable by default. That means
eliminating the generic seek() method.
A common pattern in bundle2.py is to seek to the end of the part
data. This is mainly used by the part iteration code to ensure
the underlying stream is advanced to the next bundle part.
In this commit, we establish a dedicated API for consuming a
bundle2 part data. We switch users of seek() to it.
The old implementation of seek(0, os.SEEK_END) would effectively
call self.read(). The new implementation calls self.read(32768)
in a loop. The old implementation would therefore assemble a
buffer to hold all remaining data being seeked over. For seeking
over large bundle parts, this would involve a large allocation and
a lot of overhead to collect intermediate data! This overhead can
be seen in the results for `hg perfbundleread`:
! bundle2 iterparts()
! wall 10.891305 comb 10.820000 user 7.990000 sys 2.830000 (best of 3)
! wall 8.070791 comb 8.060000 user 7.180000 sys 0.880000 (best of 3)
! bundle2 part seek()
! wall 12.991478 comb 10.390000 user 7.720000 sys 2.670000 (best of 3)
! wall 10.370142 comb 10.350000 user 7.430000 sys 2.920000 (best of 3)
Of course, skipping over large payload data isn't likely very common.
So I doubt the performance wins will be observed in the wild.
Differential Revision: https://phab.mercurial-scm.org/D1388
test that we don't interrupt the merge session if
a file-level merge failed
$ hg init repo
$ cd repo
$ echo foo > foo
$ echo a > bar
$ hg ci -Am 'add foo'
adding bar
adding foo
$ hg mv foo baz
$ echo b >> bar
$ echo quux > quux1
$ hg ci -Am 'mv foo baz'
adding quux1
$ hg up -qC 0
$ echo >> foo
$ echo c >> bar
$ echo quux > quux2
$ hg ci -Am 'change foo'
adding quux2
created new head
test with the rename on the remote side
$ HGMERGE=false hg merge
merging bar
merging foo and baz to baz
merging bar failed!
1 files updated, 1 files merged, 0 files removed, 1 files unresolved
use 'hg resolve' to retry unresolved file merges or 'hg update -C .' to abandon
[1]
$ hg resolve -l
U bar
R baz
test with the rename on the local side
$ hg up -C 1
3 files updated, 0 files merged, 1 files removed, 0 files unresolved
$ HGMERGE=false hg merge
merging bar
merging baz and foo to baz
merging bar failed!
1 files updated, 1 files merged, 0 files removed, 1 files unresolved
use 'hg resolve' to retry unresolved file merges or 'hg update -C .' to abandon
[1]
show unresolved
$ hg resolve -l
U bar
R baz
unmark baz
$ hg resolve -u baz
show
$ hg resolve -l
U bar
U baz
$ hg st
M bar
M baz
M quux2
? bar.orig
re-resolve baz
$ hg resolve baz
merging baz and foo to baz
after resolve
$ hg resolve -l
U bar
R baz
resolve all warning
$ hg resolve
abort: no files or directories specified
(use --all to re-merge all unresolved files)
[255]
resolve all
$ hg resolve -a
merging bar
warning: conflicts while merging bar! (edit, then use 'hg resolve --mark')
[1]
after
$ hg resolve -l
U bar
R baz
$ cd ..